A top aide to the Palestinian intelligence chief was killed today in a car explosion, in what Palestinian officials said was a targeted attack by Israel.

The Israeli army had no immediate comment.

Col. Tayser Khattab, 52, was driving toward his office at Palestinian intelligence headquarters north of Gaza City when his car exploded. Police said a bomb apparently was planted in the car and set off by remote control.

One witness, grocery store owner Ziad Sharkh, said the blast sent car parts into the air. ''I saw Khattab passing by and then a minute later I heard a big explosion and I saw fire coming from the car,'' Sharkh said.

The car split in two. Parts were found 20 yards away from the site. A car seat landed more than 10 yards away.

Khattab was taken to Shifa Hospital in Gaza City in critical condition but died soon after, said Dr. Moawi Hassanan.

A bodyguard was critically injured.

Khattab was a top aide to the Palestinian intelligence chief, Amin al-Hindi, and was also a member of Palestinian leader Yasser Arafat's Fatah movement. He was described as a senior bureaucrat who was very close to al-Hindi.

Al-Hindi's office said in a statement that Khattab was killed in an ''ugly assassination'' by Israel.

As one of the top Palestinian security officials, al-Hindi met sporadically throughout the 11 months of Israeli-Palestinian fighting with Israeli counterparts, as part of CIA-led efforts to restore security cooperation between the two sides.

However, the most recent meetings earlier this summer broke down, with each side holding the other responsible for the ongoing violence.

An Israeli army spokesman, Lt. Col. Olivier Rafowicz, would not comment on the car explosion.

Since the outbreak of fighting, about 50 Palestinians have been killed in targeted Israeli attacks. Most were militants suspected of planning attacks on Israelis. However, several bystanders, including women and children, have also been killed.

Israel has acknowledged some of the killings, including attacks in which helicopter gunships fired missiles at the targeted men.

Palestinian police have said that in some other cases, Israeli agents, with the help of collaborators, planted bombs in phone booths or cars of Palestinians singled out for killing. Israel generally has not acknowledged involvement in those attacks.